title: Extracellular Hsp70 inhibits pro-inflammatory cytokine production by IL-10 driven down-regulation of C/EBPβ and C/EBPδ.
abstract: OBJECTIVE
  Extracellular Hsp70 has anti-inflammatory potential, demonstrated in different models of inflammatory diseases. We investigated probable mechanisms used by Hsp70 to down-regulate pro-inflammatory cytokines.
  
  
  METHODS
  We analysed cytokine mRNA levels in bone marrow-derived murine dendritic cells treated with Hsp70, lipopolysaccharide (LPS) and peptidoglycan (PGN) or OVA (an irrelevant protein control), hypothesising that this was mediated by C/EBPβ and C/EBPδ transcription factors. We also tested the involvement of TLR2, IL-10, ERK and STAT3, using genetically deficient mice and pharmacological inhibitors.
  
  
  RESULTS
  C/EBPβ and C/EBPδ levels were inhibited in bone marrow derived dendritic cells (BMDCs) treated with Hsp70, and that correlated with inhibition of TNF-α, IFN-γ and MCP-1. Such inhibition was not observed in TLR2 or IL-10 knockout mice, and was also abrogated upon pretreatment of cells with ERK and JAK2/STAT3 inhibitors.
  
  
  CONCLUSIONS
  C/EBPβ and C/EBPδ transcription factors are inhibited by Hsp70 treatment, and their inhibition occurs via the TLR2-ERK-STAT3-IL-10 pathway in BMDCs, mediating the anti-inflammatory effects of Hsp70.
authors.affiliation: School of Biosciences and Biomedical Research Institute, Pontifícia Universidade Católica do Rio Grande do Sul , Av. Ipiranga, 6690, Porto Alegre, Rio Grande do Sul , Brazil.
authors.forename: Thiago J
authors.initials: TJ
authors.lastname: Borges
authors.forename: Rafael L
authors.initials: RL
authors.lastname: Lopes
authors.forename: Nathana G
authors.initials: NG
authors.lastname: Pinho
authors.forename: Felipe D
authors.initials: FD
authors.lastname: Machado
authors.forename: Ana Paula D
authors.initials: AP
authors.lastname: Souza
authors.forename: Cristina
authors.initials: C
authors.lastname: Bonorino
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics*; D051743:CCAAT-Enhancer-Binding Protein-delta / Q000235:genetics*; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D020935:MAP Kinase Signaling System; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010047:Ovalbumin / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D022782:CCAAT-Enhancer-Binding Protein-beta; C545013:Cebpb protein, mouse; C497253:Cebpd protein, mouse; D016207:Cytokines; D018840:HSP70 Heat-Shock Proteins; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D051743:CCAAT-Enhancer-Binding Protein-delta; D010047:Ovalbumin